It shows about 22.3°C for Destiny Lab. I wonder if it is a bit warmer or cooler in their sleeping quarters. Pity there is no reading for relative humidity.
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Andrey SokolovNov 3 '13 at 0:03

The air temperature is 72°F (22°C) according to Tracy Caldwell Dyson (see youtube.com/watch?v=030_pKgXUI8 at about 13:55) but she also says "sometimes it gets a little cold". This matches the live data from the page Deer Hunter posted a link to.
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Andrey SokolovDec 15 '13 at 4:39

Temperature and Humidity and Control subsystem helps maintain a
habitable environment in the Station by removing heat and humidity,
and circulating the cool dry air. Circulation of the atmosphere
minimizes the temperature variations, ensures a well-mixed, breathable
atmosphere and supports smoke detection;

Regenerative Environmental Control and Life Support System (ECLSS) Diagram (Source: NASA Science News)

The ECLSS is however a complex system and many of its parts failed on multiple occasions, for example the Oxygen Generation System (OGS) triggered several alarms, both the old one and its replacement that was activated in 2007. Now, this wasn't so critical because of redundancy in life support systems onboard the ISS, and e.g. the Russian segment has a Life Support Systems (LSS) too. So this should hopefully answer your question if the air temperature and humidity levels have ever been adjusted. With replacements and parts of individual systems failing these levels would obviously vary substantially at least on some segments of the ISS. And with many isolated systems, they would also vary segment to segment, module to module. Leaving the description of the complexity of all these systems to another document on ECLSS from the European Space Agency (ESA) from 2010 (also PDF):

Several Life Support systems are accommodated at the ISS to safely
sustain its crew in conditions similar to those on the Earth. They
are distributed amongst the ISS modules. Specific differences exist
between the equipment located in the US and Russian Segment.

Finding actual nominal performance quotes is a bit more tricky though with possibly many standalone systems active at the same time in different segments of the ISS. For example for the Russian segment, these are the quoted values:

Basic values of parameters of the atmospheric composition of the Russian segment, taking into account the gas exchange between the human body and the environment, fall within the following limits:

All Temperatures listed are in °C. To my knowledge, there is no archived or live telemetry data stream of all the sensor readings from the ISS available to public.

TL;DR - It's ... complicated. ;)

Update: Some of the ETHOS (Environmental and Thermal Operating Systems) Life Support, Thermal System and Regenerative Life Support data on The Space Station Live NASA's web page is finally available, so it should help you get an overview. It should be mentioned tho, that it doesn't include any telemetry data on the Russian segment of the ISS, and excludes large number of individual sensor readings, presenting per module current average values (with not all modules listed).

I am interested in the results of actual measurements inside the ISS, rather than nominal ranges of various climate control systems, although that info is also relevant and much appreciated. I am sure they have thermometers and humidity sensors inside the station.
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Andrey SokolovOct 27 '13 at 4:54

1

@Andrey They have several dozen of sensors per each module, on the internal and external THC loops. As mentioned, there are also multiple standalone THC systems. Short of hacking into the ISS telemetry data stream, decrypting it and making sense of it all, I have no knowledge of how to get to actual live readings. I didn't find any archives of the readings available to the public either, short of what is quoted in numerous documents where environmental control systems are discussed. I've extended my answer and emphasised a few points a bit, which should cover it as much as it is possible here.
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TildalWave♦Oct 27 '13 at 9:54

The document you mention from my answer is by Dr. Bacal that worked for several years at Johnson Space Center in the branch of Medical Informatics and Health Care Systems and is an active member of Space Medicine Associates. The document itself should cover its applicability well enough. The linked to chapters are from a pre-press version of Bacal, Beck, and Barratt, “Hypoxia, Hypercapnia, and Atmospheric Control”, in Textbook of Aerospace Medicine, ed. Barratt and Pool, Springer-Verlag.
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TildalWave♦Oct 27 '13 at 10:15